Abstract Detail

Phylogeny and biogeography of the widespread genus Melicope and related genera (Rutaceae).

The genus Melicope (Rutaceae) comprises about 230 species, subdivided into four sections. Its distribution ranges from SE Asia, the Malesian region, Australia, to Pacific islands, including the Hawaiian Islands. Apart from that Melicope also occurs in Madagascar and the Mascarene Islands, making the distribution largely disjunct. The centers of species richness and endemicity in Melicope are New Guinea with 58 species (44endemic), and the Hawaiian Islands with 48 endemic species. For a long time there has been confusion about the relationships and generic delimitations of Melicope towards the genera Acronychia and Euodia. In his revision work, Thomas Hartley hypothesized a close relationship between Melicope and Acronychia despite them being placed indifferent subfamilies of Rutaceae by most other taxonomists. Hartley also reduced Euodia from about 200 species to seven species and transferred most species to Melicope and Tetradium. Our preliminary molecular phylogenetic studies on Melicope and related genera based on both plastid (trnL-trnF, psbA-trnH, atpB-rbcL spacer) and nuclear markers (ITS, AT103) largely support Hartley's view. Melicope and Acronychia are resolved as sister genera with high support and Euodia as sister to both. Former Euodia species included in our studies belong to Melicope and Tetradium. A number of monotypic or small genera related to the Melicope-Acronychia-Euodia clade have been described mainly from New Caledonia and New Guinea. Our studies show that some of them have to be included in Melicope (Comptonella, Platydesma, Picrella, Sarcomelicope), while others are closely related to Euodia (Brombya, Perryodendron, Pitaviaster). Further results of our on-going studies are that Melicope and its four sections are monophyletic if the above-mentioned genera are included and that the disjunct species from Madagascar and the Mascarene Islands clearly belong to Melicope and thus deliver a further case of a long-distance dispersal between SE Asia and Madagascar. Although our current dataset covers the whole distribution range of Melicope, our taxon sampling is still limited to about 30 percent. However, we have a dense taxon sampling for the Hawaiian Islands in which 33 (mostly with more than one accession) out of the 48 described species (of which five are considered extinct and 17 assessed as vulnerable or endangered) are included.